Dashpot



7 1959 A. H. WINKLER 2,915,303

DASHPOT Fi ed March so, 1955 2 Sheets-Sheet 2 IN V EN TOR.

United States Parent O I DASHPOT Albert H. Winkler, Elmira, N.Y., assignor to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application'March so, 1955, Serial No. 497,833

1 Claim. c1. 261-34) This invention pertains to carburetors for internal combustion engines and more particularly to fluid displacing apparatus such as may be used in dashpots or accelerating pumps associated with said carburetors.

One of the major difficulties encountered in fuel dashpots and accelerating pumps is the maintenance of liquid fuel in the chamber below the piston after the carburetor has been heated. In the ordinary dashpot or accelerating pump when the fuel is heated, vapor forms below the piston and renders the duration of dashing action or pump discharge uncertain. It has been suggested in the past to provide a vent in the piston to allow the gases to escape. These vents have been provided with various types of valves to close the vent during the operation of the piston. The valves used in the past have not provided a desirable solution because of their increased intricacy and expense and somewhat irregular operation. Generally these valves have been seated by the force of fluid pressure as the piston is moved in a fluid displacing direction. Because of poor mechanical fits resulting in irregular frictional drag, the seating of the valve has not been such as to provide consistent results from the actuation of the piston. An effective valve of this type must also be carefully made and is subject to wear which causes leaks.

An object of the present invention is to provide a fluid displacing apparatus having a piston provided with an aperture for ready escape of vapors which is adapted to be closed by a separate actuating member during the fluid displacing stroke.

Another object of this invention is to provide an improved dashpot construction having uniform resistance during actuation and which remains unaffected by the formation of vapor in the device.

Other objects and advantages of the invention will be readily apparent from the consideration of the following description taken in connection with the accompanying drawings, in which:

Figure 1 is a top view of a carburetor embodying my invention;

Figure 2 is a view taken along line 2-2 of Figure 1;

Figure 3 is a view taken along line 3-3 of Figure 1; and

Figure 4 is a view showing the dashpot taken along line 44 of Figure 1.

Referring now to the drawings, numeral 10 designates a carburetor, 12 a main body, 14 an induction passage with a choke valve 16 and a throttle valve 18 mounted therein on shafts 20 and 22 respectively. A fuel bowl 24 is formed in body 12 and contains a float 26 which maintains a fuel level at a predetermined height shown by the line xx. A pair of main jets 28 and 30 communicate with bowl 24 below the normal fuel level therein and are adapted to discharge into boost venturis 32 and 34 located in mixture chambers 36 and 38 which are defined by large venturis 40 and 42 respectively.

As best shown in Figure 3, an accelerating pump 44 is located in main body 12 adjacent fuel bowl 24 includes a well or housing 46, a fuel displacing member,

2,915,303 Passes-ea; 1.1

I an outlet 56 having a check valve 58. A passage 60 connects inlet 54 with fuel bowl 24. Conduit 62 connects outlet 56 to discharge nozzles 64 in the induction passage. A rod 66 connects actuating member 50 with lever 68 which is-connected to throttle lever 70 which in turn is secured to shaft 22. A spring 72 urgespiston 48 in the fluid intake direction. An abutment or snapring 74 limits the movement of the piston in this direction.

In describing the operation of the device, the parts of the accelerating pump assume the position shown in Figure 3 when the device is at rest or inoperative. As shown in the drawing, actuating member 50 is spaced from piston 48 so as .to permit any vapors formed in well 46 to readily escape through aperture 49 in the piston. Upon actuation of the throttle lever 70 the actuating member 50 is moved into engagement with the piston 48 closing the aperture 49 whereupon continued downward movement of the piston and actuating member displaces fuel and forces it out through nozzles 64. The snap ring 74 and the linkage 66 and 68 may be accurately positioned and constructed so that the actuating member 50 will pick up piston 48 in an accurately predetermined position to permit the accurate calibration of said pump.

In Figure 4 there is shown a dashpot embodying my invention. Dashpot 80 includes a cylinder or housing 82 located in main body 12 and adapted to communicate with fuel bowl 24 through a conduit 84 which is provided with a check valve 86. A piston or movable wall 88 having a centrally located aperture 90 is reciprocably disposed in housing 82. Spring 92 urges piston 88 upwardly to a limited position determined by an abutment such as snap ring 94. Above piston and normally spaced therefrom is an actuating member 96 having a calibrated passage 98 therethrough which is adapted to register with aperture 90. A rod 100 connects actuating member 96 to lever 68 so that the member 96 is moved downwardly when the throttle valve is moved toward closed position.

In the operation of the device, the parts of the dash pot assume the position shown in Figure 4 when the throttle valve 18 is in at least a partially opened position. In the position shown the dashpot is inactive and vapors formed below piston 88 may readily escape through aperture 90 and around actuating member 96. When the dashpot is actuated by a closing movement of the throttle, the actuating member 96 moves into engagement with piston 88 sealing off aperture 90 and preventing flow from one side of the piston 88 to the other except through calibrated passage 98. The size of passage 98 may be accurately determined and with the vapors eliminated by the aforementioned means the action of the dashpot is rendered certain and consistent.

The details of the invention shown and described are by way of example only, and may be varied to meet specific conditions within the teaching of the invention.

I claim:

In a carburetor having a throttle and a fuel bowl with float actuated valve means for maintaining a predetermined fuel level therein a dashpot comprising a cylinder communicating at its lower end with said fuel bowl and extending at its other end above the fuel level in said bowl, a movable wall in said cylinder dividing the interior thereof into upper and lower chambers, means defining a normally open aperture in said wall, a spring in said lower chamber urging said wall in one direction, an abutment in said cylinder limiting the movement of said wall in said one direction, an actuating member in said cylinder separate from said wall and normally spaced therefrom whereby-fuel and vapor may flow unrestrictedly through'said aperture defining means, a calibrated passage in said actuating member, a connection between said throttle and said actuating member for moving said actuating member into engagement with said wall and formovin'g saidwall in'a'di'rection opposite to said one direction when said throttle is moved toward closed position, said member being formed to register with said aperture defining means when said member and said wall are in engagement whereby said calibrated passage forms the sole communication between said upper and lower chambers.

" 1,513,016 St. John Oct. 28, 1924 4 Lis'sen Mar." 23, Weinbrunn Feb. 11, Hurst Dec. 15, Trisler Oct. 27, Whisler Aug. 8, Ainslie et al. Oct. 10, Parker et a1. Dec. 10, Parker et a1. Sept. 28, Lee Oct. 5, Engstrom Mar. 8, Hunt July 1, Olson Apr.. 21, Koski et a1. Jan. 3, 

